Obi Wan Kirk:
Manchester Airport is not used much
Are you talking about Manchester UK (MAN) here?
If so, you are somewhat misinformed, as MAN is a fairly busy airport with 60+ airlines operating scheduled and charter flights to worldwide destinations.
Ryanair are only one of three operators who currently serve Dublin from Manchester, the others being Aer Lingus (codeshare with BA) and Luxair.
Why should they get preferential treatment?